1. Field of the Invention
The present invention relates to a thin-film magnetic head which is employed for reading or recording information in a magnetic disk unit or the like. The present invention also relates to a method of forming a carbon film on a substrate by electron cyclotron resonance (ECR) plasma CVD, and more particularly, it relates to a method of forming a carbon film on a substrate while applying a high-frequency voltage thereto.
2. Description of the Background Art
A thin-film magnetic head, which has an excellent frequency response and can make high-density recording by refining the track width and the bit length, is employed as a magnetic head for a magnetic disk unit or the like.
When a magnetic recording medium is started and rotated, the thin-film magnetic head is slightly upwardly separated from the medium so that a circulating air film is defined between a slider surface of the thin-film magnetic head and the magnetic recording medium. When the operation of the magnetic recording medium is stopped, the slider surface of the thin-film magnetic head comes into direct contact with the magnetic recording medium. Therefore, the slider surface of the thin-film magnetic head must have abrasion resistance. Further, a thin-film transducer portion which is formed by a magnetoresistive element or the like is easy to corrode, and hence it is necessary to protect this portion.
Japanese Patent Publication No. 6-18054 (1994) proposes a method of forming a film of molybdenum disulfide or the like on a surface of a thin-film magnetic head facing a magnetic recording medium, i.e., a slider surface. This gazette discloses a method of forming a film of molybdenum disulfide or carbon having a thickness of 200 to 800 .ANG. on a slider surface of a thin-film magnetic head. It is possible to improve abrasion resistance and corrosion resistance by forming such a protective film.
However, the conventional thin-film magnetic head provided with such a protective film disadvantageously has a problem of extreme output reduction particularly in a high linear density region.
In magnetic recording employing a magnetic disk or the like, higher densification is required, and a thin-film magnetic head which can cope with such requirement is awaited.
On the other hand, a carbon film such as a diamond-like carbon film, which is employed as a protective film for a magnetic disk, a magnetic head or an optical part, is formed on a substrate by ECR plasma CVD, for example.
In such formation of a carbon film by ECR plasma CVD, a microwave is introduced into a plasma chamber while a gas containing carbon is introduced into a reaction chamber. In the plasma chamber, the frequencies of electrons rotated by a magnetic field and of the microwave coincide with each other to cause electron cyclotron resonance, thereby generating a plasma of high density. This plasma is introduced into the reaction chamber for decomposing the gas containing carbon in the plasma, thereby forming a carbon film on a substrate.
Such a carbon film having excellent abrasion resistance and corrosion resistance is formed as a protective film on a slider surface of a thin-film magnetic head which is relatively moved on a magnetic recording medium for reading and writing information from or to the medium (Japanese Patent Laying-Open No. 4-276367 (1992) etc.).
However, the plasma chamber is provided with an electromagnetic coil etc. applying a magnetic field, which exerts a damaging influence on the thin-film magnetic head and may break the head or deteriorate its performance.
On the other hand, the carbon film may be formed with application of a high-frequency voltage to the substrate so that the film is improved in adhesion. When the applied high-frequency voltage is increased in this case, however, the temperature of the substrate is disadvantageously increased to heat the thin-film magnetic head to a high temperature. Thus, the thin-film magnetic head is broken or its performance is deteriorated by heat.